A non-aqueous electrolyte secondary battery represented by a lithium-ion secondary battery is drawing attention as a power supply with large capacity mainly for portable equipment. Recently, to further increase the capacity of such a battery, development of electrode materials (use of active materials having large capacity density and reduction of additional materials) and improvement of structural parts (for example, reduction of thickness) have been made actively.
Among the electrode materials, Si and Si compounds to be used as a negative electrode active material are the materials having large capacity of which theoretical capacity is much higher than that of graphite. For this reason, modifying research on Si and Si compounds is attempted for utilization thereof. Reported examples of this research include a non-aqueous electrolyte secondary battery that uses a thin film of Si formed on a current collector of a copper foil or the like (see Patent Document 1, for example), and a non-aqueous electrolyte secondary battery that uses a Si oxide having a lower capacity but longer life than Si as the negative electrode active material (see Patent Document 2, for example).
Generally, Si and Si compounds used as a negative electrode active material produce an extremely large irreversible capacity. The irreversible capacity results from the amount of lithium that is stored at charging but is not released at discharging. Thus, to uniformly compensate for the irreversible capacity, the following method is proposed. An electrode body is formed so that the surface of the negative electrode thereof has a dispersion coating of lithium powder. Then, when an electrolyte solution is poured, a local cell is formed to cause the negative electrode to store lithium. To disperse lithium powder on the surface of the negative electrode in this manner, the following method is proposed (see Patent Document 3, for example). A liquid dispersion containing lithium powder dispersed in a volatile dispersing medium is applied to the negative electrode and dried.
However, to make the negative electrode securely hold the amount of lithium powder necessary to compensate for the irreversible capacity of the negative electrode active material, a binder should further be added to the liquid dispersion. When a binder is not used, it is highly possible that lithium powder fall off from the negative electrode in the step of forming the electrode body. On the other hand, when a binder is used, the binder remains on the surface of the negative electrode and increases internal resistance.    Patent Document 1: Japanese Patent Unexamined Publication No. 2002-83594    Patent Document 2: Japanese Patent Unexamined Publication No. H06-325765    Patent Document 3: Japanese Patent Unexamined Publication No. 2005-317551